Trilobites

Trilobite, Asaphiscus wheeleri [Wheeler Shale/Middle Cambrian]

Trilobites are an extinct class of arthropods defined by distinctive three-lobed, three-segmented forms. Evidence of their existence dates back to the beginning of the Cambrian Period 542 million years ago. They dominated the seas until their extinction during the Great Dying, the most severe extinction event which occurred between the Triassic and Permian Period 251.4 million years ago. Fossils of these creatures have been found on every continent, with areas such as the Wheeler Shale in Utah, the Emu Bay Shale in Australia, the Burgess Shale in British Columbia, and the Chengjaing Formation in China as being notable locations to find trilobites. They ranged in size from 1 cm to 70 cm (28 in), had a flower-like eye, and a thick chitinous exoskeleton which was shed often. There are currently over 20,000 recognized species of trilobites organized into 10 different orders.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.